1. Field of the Invention
The present invention relates to a novel polymer for water treatment, an agent for water treatment containing the polymer for water treatment, a process for treating water which comprises adjusting concentration of the polymer for water treatment in water for treatment, and a novel process for producing a polymer for water treatment. More particularly, the present invention relates to a labeled polymer for water treatment concentration of which in water can be measured conveniently, accurately and quickly, application of the labeled polymer for water treatment, and a process for producing the polymer for water treatment by which the labeled polymer for water treatment can be produced under atmospheric pressure.
2. Description of the Related Art
Recently, various kinds of polymer are added to boiler water, cooling water and the like for the purpose of preventing scale formation and corrosion. As such polymers, for example, acrylic acid polymers, maleic acid polymers and acrylamide polymers are used. For exhibiting the effect, concentration of the polymer is generally about 1 to 100 mg/liter. When such polymers are used, it is desirable that concentration of the polymer in water is kept at the minimum value sufficient for exhibiting the effect. Addition of an excess amount of the polymer is not only economically disadvantageous but also causes problems that load for waste water treatment is increased and that the effect is even decreased depending on the kind of polymer. The concentration of the polymer is decreased because the polymer in water is consumed in the system and, at the same time, lost together with the waste water discharged from the system. Therefore, it is necessary that the concentration of the polymer in the system is measured and the polymer is added to the system in an amount adjusted to keep the concentration at the optimum value.
As the method of measuring concentration of a polymer in water, for example, colormetric method, turbidimetric method, lithium tracer method and fluorescent tracer method are known. However, the colorimetric method and the turbidimetric method are conducted by manual operation because automatic operation is difficult with these methods and have a drawback that the measurement requires a long time. Measurement with the tracer methods can be conducted in a short time and automatic operation is possible. However, they have a drawback in that they cannot show consumption of the polymer in the system because the measurement is made not with the polymer itself but with another compound (a tracer) which is added simultaneously and easily measured.
As described above, the conventional methods of measurement have a drawback in that they cannot achieve accurate and quick measurement of a polymer in water and, therefore, amount of the addition of the polymer to the system cannot be adjusted automatically in response to changes in the concentration of the polymer in water.
For overcoming these drawbacks, the present inventors has proposed a polymer for water treatment labeled with a fluorescent substance (Japanese Patent Application Laid-Open No. Heisei 5(1993)-163591). However, the proposed polymer for water treatment has a drawback in that intensity of the fluorescence rapidly diminishes by the effect of the sunlight and the polymer is not always satisfactory. A polymer having a side chain group of sulfonated naphthalene labeled with a fluorescent substance is disclosed in Japanese Patent Application Laid-Open No. Heisei 4(1992)-233918. The side chain group is introduced into a polymer having a carboxyl-type side group by transamidation reaction.
However, the transamidation reaction requires an environment of a high temperature and a high pressure and is not preferable in view of safety.